Paper machines may use multiple, sometimes multiple dozens or even hundreds, of rope sheaves as part of a rope carrier system. The rope threaded through these sheaves may be used, e.g., to thread paper tail into a paper machine. The rope carrier generally includes two ropes driven by the machine or an external driver, with the sheaves being idlers that are driven by the ropes.
Generally, the sheaves rely on a simple rotational support system. Two deep-groove ball bearings are disposed within a hub of a sheave body. The outer diameter of the bearing forms a light interference fit with the sheave body. A shaft is received through the inner diameter of the bearing ring, such that the sheave is supported and rotatable relative to the shaft.
The bearings are lubricated with grease, and typically maintaining the carrier system includes replacing the bearing grease, which may become contaminated. Such re-lubrication may require the machine to be brought to a standstill, which can leave the sheaves susceptible to corrosion. Further, sheaves in the “wet” section of the paper machine may experience high humidity, which may further corrode the bearings, while sheaves in the “dry” section may operate at high temperatures and in dusty environments, which may reduce the life of the grease. The sheaves may also be located in difficult to reach sections of the machine.
Thus, it may be desired to reduce the frequency with which the bearings are re-lubricated. One way this is handled is by over-lubricating the bearings. This can lead to leakage, which may manifest as spots on the paper product. Further, the sheaves of a single machine and/or multiple machines may come in a variety of sizes, and thus modifying the sheaves to avoid some of the aforementioned challenges may be costly.